1. Field of the Invention
The present invention relates to vacuum cabin door technology, and more particularly to a self-lockable opening and closing mechanism for vacuum cabin door, which automatically produces a locking force to lock the vacuum cabin door in position when the vacuum cabin door is closed.
2. Description of the Related Art
In semiconductor industry involving wafer fabrication or TFT LCD production, glass substrates are normally processed in a vacuum environment, for example, in a vacuum cabin. A vacuum cabin generally comprises a vacuum cabin door drivable by an opening and closing mechanism between an open position and a close position. When the vacuum cabin door is opened, the workpiece can be moved over the vacuum cabin door into the inside of the vacuum cabin. After the workpiece is delivered into the inside of the vacuum cabin, the vacuum cabin door is closed, and then a pumping operation is performed to draw air out of the vacuum cabin.
An opening and closing mechanism for vacuum cabin is known using a pneumatic cylinder or hydraulic cylinder to move the vacuum cabin door between the open position and the close position either directly or through a rack and gear mechanism. However, when the vacuum cabin door is moved to the close position, the pneumatic or hydraulic cylinder must keep giving pressure to the vacuum cabin door panel against the cabin door frame, keeping the vacuum cabin door in the close position. However, after a long use of the machine, a wear problem may occur, and the pneumatic or hydraulic pressure of the pneumatic or hydraulic cylinder may become insufficient due to pipeline problems, resulting in sealing failure between the vacuum cabin door and the vacuum cabin.
Taiwan Patent TW430012 discloses a vacuum cabin door opening and closing mechanism, which comprises a frame, a first pneumatic cylinder affixed to the frame, a second pneumatic cylinder affixed to the first pneumatic cylinder and movable up and down relative to the first pneumatic cylinder, a vacuum cabin door, and a linkage coupled between the vacuum cabin door and the second pneumatic cylinder. During operation, the first pneumatic cylinder is driven to move the second pneumatic cylinder and the vacuum cabin door upwardly into alignment with the vacuum cabin, and then the second pneumatic cylinder is retracted, driving the linkage to move the vacuum cabin door horizontally toward the vacuum cabin, and thus the vacuum cabin is closed by the vacuum cabin door. According to this design, it is necessary to move the vacuum cabin door vertically and horizontally through two actions, prolonging the operation time and increasing the structural dimension and cost.
Further, CN 101787834 B discloses an opening and closing device for horizontal vacuum cabin, which has multiple auto locking mechanisms mounted at the outside wall around the opening of the vacuum cabin for locking the vacuum cabin door to the vacuum cabin in the close position. However, this design is not a perfect solution because the opening and closing device and the auto locking mechanism must be separately driven and controlled.